1. Cellular Transport

2. TEM picture of a real cell membrane.
Cell Membranes
1. All cells have a cell membrane
2. Functions:
Controls what enters and exits the cell to maintain an internal balance called homeostasis.
Provides protection and support for the cell
TEM picture of a real cell membrane.

3. Cell Membranes (continued)
3. Cell membranes have pores (holes)
a. Selectively permeable: Allows some molecules in and keeps other molecules out
b. The structure helps it be selective!
Pores
Pores
Pores

4. Cellular Transport!
The process by which molecules are moved from one side of the cell membrane to the other.
Two Types:
Active
Passive

5. Types of Cellular Transport
Animations of Active Transport & Passive Transport
high
low
Weeee!!!
Passive Transport
cells do not use energy
Diffusion
Osmosis
Active Transport
cells do use energy
Endocytosis
Exocytosis
high
low
This is going to be hard work!!

6. Passive Transport Cell uses no energy. Molecules move randomly.
Molecules spread out from an area of high concentration to an area of low concentration.
(HighLow)
Two types: osmosis and diffusion

7. Passive Transport: 1. Diffusion
Simple Diffusion Animation
Passive Transport: 1. Diffusion
Diffusion: random movement of particles from an area of high concentration to an area of low concentration.
(High to Low)
Diffusion continues until all molecules are evenly spaced (equilibrium is reached)-Note: molecules will still move around but stay spread out.

8. Passive Transport: 2. Osmosis
Osmosis animation
2. Osmosis: diffusion of water through a selectively (semi) permeable membrane
Water moves from high to low concentrations.
Water moves freely through pores.
Solute (green) to large to move across.

9. Active Transport Actively moves molecules to where they are needed.
Cell uses energy.
Actively moves molecules to where they are needed.
Movement from an area of low concentration to an area of high concentration
(Low  High)
Two Types: endocytosis and exocytosis

10. Active Transport: Endocytosis and Exocytosis
Allow for the passage of food and waste particles that are too big to pass through the cell membrane and protein channels.

11. Types of Active Transport
Endocytosis: takes bulky material into a cell
uses energy
cell membrane in-folds around food particle
“cell eating”
forms food vacuole & digests food
This is how white blood cells eat bacteria!

12. Endocytosis Membrane folds in and forms a vesicle.
(endo- means inside)
Membrane folds in and forms a vesicle.
Contents are digested by cellular enzymes .

13. Types of Active Transport
Exocytosis: forces material out of the cell in bulk
membrane surrounding the material fuses with cell membrane
cell changes shape – requires energy
Example: hormones or wastes released from cell
Endocytosis & Exocytosis animations

14. Exocytosis The substance (food, waste, etc.) packaged into vesicle.
(exo- means outside)
The substance (food, waste, etc.) packaged into vesicle.
The vesicle fuses with the cell membrane.
The substance is released from cell.
Inside Cell
Outside Cell
Cell Membrane

15. Putting it all together
Explain the difference between passive and active transport?
How do cells obtain the materials they need to perform life processes?